EchiocerasEchioceras is an extinct genus of ammonites from the Early Jurassic of Europe and North America.DescriptionShell of Echioceras species can reach a diameter of about.. The narrow and broad evolute shell is reinforced by fine ribs on inner whorls, progressively becoming stronger, straight and distinct.DistributionFossils of species within this genus have been found in the Jurassic rocks of Canada, Hong Kong, Turkey and United Kingdom, Carpathians and Alps.